Expansible bit.



T. E. POPE, Y EXPANSIBLE BIT.

' APPLICATION EILED 0013.19, 1908.

988,143. Patented Mar. 28, 1911.

" i llllllElllllii l'llli i WITNESSES I 1 INVENTOR I ma. 5, F7 4, l' BY "111 1! [1 w AITIORNEY UNIED STTES FFICE.

THOMAS E..POPE, OF ALAMEDA, CALIFORNIA", ASSIGNOR TO LOUREY-POPE MANUFAC- TURING COMPANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION.

EXPANSIBLE BIT.

988,143. Specification of Letters Patent Patented Mar. 28, 1911.

Application filed October 19, 1908. Serial N 0. 458,353.

To all whom it may concern:

Be it known that I, THOMAS E'. Porn, a citizen of the United States, residing at Alameda, in the county of Alameda and State of California, have invented new and useful Improvements in Expansible Bits, of which the following is a specification.

The objectof the present invention is to provide a bit which can be expanded while the work is progressing tobore a recess or socket expanding inwardly. The utility of such a bit resides in the fact that a socket of this form is very advantageous for securing therein the end of a cylindrical bar, rod, or other connection, as said end can be caused, by a wedge located centrally in the end of bar, or other connection, to spread and fill the socket thus formed, and thus make a firm and durable attachment of said bar or other part in said socket. Furthermore, since a bit of this character can be used for boring holes of many different sizes, the number of tools required for boring holes of all sizes, is thereby reduced.

In the accompanying drawing, Figure 1 is a side view of a bit constructed in accordance with my invention; Fig. 2 is a cross section on the line 2-2 of Fig. 1; Fig. 3 is a broken longitudinal section through the working end of the bit; Fig. at is a broken longitudinal section taken transversely of the cutter; Fig. 5 is an end view of the tube detached; Fig. 6 is a perspective view of the cutter detached.

Referring to the drawing, 1 indicates a cylindrical stem, adapted to be turned in the usual manner by a crank handle, not shown. At the power end the stem is screwed, as shown at 2, into a square shank 3, so that the latter can be detached, When desired, to remove the parts which normally surround the stem of the bit. The head t of the bit,'at the working end of the stem, is formed with a central lead screw 5, and, above said lead screw with a transverse slideway 6, in which can slide a bit or cutter 7, which is formed with a lateral rib S sliding in a corresponding groove in one of the faces of the slideway 6. Fitting closely around said stem is a tube 9, the lower end of which is enlarged and has formed, upon the face opposite to the cutter 7, a spiral rib 10, and the upper side of said cutter is formed with teeth 11 which are engaged by said spiral rib 10. The result is that, if the bit stein rotates while the tube is held stationary, the engagement of sald teeth 11 with said spiral rib 10' causes the cutter to move outward in its slideway, and thus to enlarge the diameter of the bore made by the cutter.

If it be desired that the hole should eX- pand very rapidly as it increases in depth, it is only necessary to hold the tube '9 stationary during the whole time that the bit is being turned, but, in making the'teeth 11 sufliciently strong to resist the pressure upon the cutter, there is a minimum limit to the thickness which can be given to said teeth, and since for each complete turn of the bit, the cutter is moved outward through a distance equal to the thickness of one tooth, a hole thus formed would generally expand too rapidly. To avoid this, the operator may from time to time release this hold upon the tube, whereupon said tube will rotate with the bit, and the cutter will then not move outward. However,'I herein show means whereby although the tube rotates as well as the bit, it does so at a slower speed, whereby the hole does not expand too rapidly. For this purpose there is provided a frame 12 consisting of terminal rings 13, 14, and an intermediate ring 15, all connected by longitudinal bars 16. The ring 13 nearest the point of the bit has secured thereto a rubber ring 17 which is adapted to rest against the mate'- rial in which the hole is .to be bored and prevent the turning of said frame. Upon the inner edges of the bars 16 are formed racks 18, which are engaged by the threaded outer edge of a disk 19, having a hub secured to the tube 9. Said frame thus constitutes a nut in which said disk turns. The threaded portion 20 of the stem of the bit is screwed through the outer ring 14. The pitch of the threaded portion 20 of the stem is the same as that of the lead screw, so that, as the lead screw penetrates the hole, the threaded portion 20 of the stem' turns in the ring 14 without any tendency to move said ring and the whole frame 12 either to or away from the face of the object being bored. But the pitch of the thread of the disk 19 is greater than that of the lead screw and of the threaded portion 20 of the stem, and the efiect of this construction is to produce a rotation of the tube with the stem but at a slower speed. For, let it be supposed, for brevity of description, that the bit is boring downward. Since tile tube supported wholly by, and fits snugly on. the stem, it always rotates vith the stem unless prevented from doing so by extraneous causes. Now the elt'ect of the rotation of the stem, and therefore also of the tube, is to move the lower sides of the threads of the disk out of contact with the faces in the rack teeth immediately below them, and to press the upper sides of said threads against the under faces of the rack teeth immediately above them. it the pitch of the threads of the disk is the same as that of the stem threads, then this tendency, of the threads of the disk to press against the teeth above them is balanced or neutralized by the tact that the stem, and therefore the disk, is also descending, at a rate corresponding to the pitch oi the threads in both the disk and stem, and therefore also in the racks and in the ring 14-. But it, as in the present case, the pitch of the threads of the disk is greater than that of the stem, then the upward pressureoit the upper sides of said threads against the teeth of the rack is not so neutralized, but there is a resultant up ward pressure. This pressure, by its triction upon the disk, retards the disk until the disk has, by the descent of the stem, also descended to such an extent thatit no longer presses upward against the teeth of the rack.

The action may be more readily understood by supposing that the several parts of the act-ion take place in finite periods of time instead of in infinitesimal periods. On such a supposition, the disk, rotating at the same speed as the stem, would first be arrested, by the upper sides of its threads im pinging against the under sides of the rack teeth immediately above. The stem however, is continually moving downward, and carries also the tube and disk downward, and therefore removes the upper sides of said threads from contact with the under sides of said teeth. These parts being no longer in contact, the disk is again tree to rotate with the stem, which it immediately does, but is again, as before, arrested by the upper sides of its threads impinging against the under sides oi? the rack teeth immediately above, and so on. Of course, there is no such alternate or intermittent action, at any rate in periods of time perceptible to our observation, but the action, while practically continuous, is of the above-described character.

An important feature of the invention consists in the construction whereby the stem and tube are entirely closed against the entrance of any borings and cuttings. While the helical web is of great advantage in eittecting the discharge of such cuttings from a hole bored by the cutter, even without t helical web my invention is superior to prior terms of devices having an auger and a l l l l cutter capable of being extended transversely, because, in all of these terms, so far as I am aware, the means for so extending the cutter transversely have necessitated openings or recesses, and especially openings of variable size, into which the chips or cut-' tings can enter, and, thus accumulating in said openings, prevent the discharge of other chips and cuttings and greatly impair the efliciency and utility of the auger. In the present invention, the tube fits snugly around the stem and leaves no cavities or passages for the entry and accumulation of the herings and cuttings.

it has already been stated. that the three racks are, in effect, a nut, within which the disk 19 on the tube turns. The threaded portion 20 of the stem and the ring 14, and the disk 19 and said racks, thus constitute a differential gear, producing a slow rearward motion of the tube relatively to the stem.

lVhile the difierential gear herein shown is of the form shown for the purpose of enabling it to be operated automatically, by forming the nut for the screw of greater pitch. as a frame which engages the face of the material being penetrated, the invention is not limited to this specific construction.

I believe that I am the first to produce a relative motion of a cutter in an expansible bit by means of a slow retardation of a tube around a sleeve effected by such differential gearing, and therefore I claim the invention as of a correspondingly broad scope, and

that the nut used therewith may be of any T desired form.

By the word nut is meant the part having two dissimilar internal threads, which engage respectively the two screws, whether these threads be formed, as herein shown, by the inwardly extending teeth of racks, or, in the usual manner, on the inside of a sleeve or tube.

It is advantageous that the tube have a loose engagement with the cutter, as that of the spiral rib on the end. of the tube with the teeth on the upper side of the cutter, for this construction permits of a cutter being readily withdrawn and substituted by a new one.

I claim 1. An expansible bit comprising a stem, a cutter transversely movable in said stem, and a tube around the stem, said cutter being formed with teeth, and an end of the tube being formed with a spiral rib engaging said teeth, substantially as described.

An eXp-ansible bit comprising a stem, a cutter transversely movable in said stem, a tube around the stem, said cutter being formed with teeth, an end of the tube being formed with a spiral rib engaging said teeth, and a disk secured to the upper end of said tube, substantially as described.

3. An eXpansible bit comprising a stem, :1

lOi

cutter transversely movable in said stem, a tube around the stem, said cutter being formed with teeth, and an end of the tube being formed with a spiral rib engaging said teeth, said tube being rotatable with said stem, and means for rotating said tube with said stem but at a slower speed, substantially as described.

4. An auger bit comprising two elements,

a stem and a tube around said stem, one of said elements being formed with a transverse guide for a cutter, and a transversely movable cutter guided thereby and formed with teeth, an end of the other element being formed with a spiral rib engaging said teeth to move the cutter transversely, substantially as described. 5. The combination of two elements, a stem and a tube around said stem, one of said elements having an anger, a cutter movable transversely in a recess in said latter element, means for transversely moving said cutter, arranged to be actuated by the rotation, relative to said element, of the other element, and means for producing such relative rotation, comprising two screws of different pitches, one on each element, and a nut having threads respectively engaged by said screws, substantially as described.

6. The combination of two elements, a stem, and a tube around said stem, an auger secured to one of said elements, a cutter movable transversely in a recess in said latter element, means for transversely moving said cutter, arranged to be actuated by the retardation, relative to said element, of the other element, and means for producing such relative retardation, comprising two screws of different pitches, one on each element, and a nut having threads respectively engaged by said screws, substantially as described.

7. The combination of a stem, having an auger, a cutter movable transversely in a recess in said stem, and a device for transversely moving said cutter having threads of diiferent pitches, the stem having a part engaging one of said threads, and an element, movable relatively to the stem and operatively connected with the cutter having a part engaging the other thread, substantially as described.

8. The combination of a stem, having an auger, a cutter movable transversely in a recess in said stem, and a device for transversely moving said cutter having threads of different pitches, the stem having a part engaging one of said threads, and an element, movable relatively to the stem and operatively connected with the cutter having a partengaging the other thread, said device being provided with means for automatically controlling its rotation, substantially as described.

9. The combination of two elements, a stem and a tube rotatable around said stem, one of said elements having an anger and a transverse recess immediately above said auger, a cutter in the form of a bar free at both ends, fitting snugly in said recess and slidable therein, and means actuated by the other element, and loosely engaging said cutter bar, for so sliding said cutter by the rotation of said latter element, substantially as described.

10. An auger bit comprising two elements, one fitting closely in the other, means for moving one of said elements relatively to the other, the other element having an anger and formed, adjacent to said auger and to the end of the movable element, with a transverse guideway for a cutter, and a cutter bar, free at both ends and movable transversely therein, said cutter and the movable element having parts loosely co-engaging each other so that from the movement of said latter element in either of two opposite directions, said cutter may be correspondingly moved transversely, substantially as described.

11. A bit having a stem and a transverse recess formed in the lower end of the bit, a transversely slidable cutter in said recess, a tube around said stem formed with a helical web, and an operative connection between the lower end of said tube and said cutter, whereby when said tube is rotated on said stem, said cutter is moved transversely, substantially as described.

12. The combination of a bit-head, an extension arm guided therein and having a series of teeth, and a sleeve surrounding the shank of the bit and having an inclined portion to engage said arm, whereby rotation of said sleeve may move said arm endwise, substantially as described.

13. The combination with a bit of a cutting arm guided therein so as to be adjustable in or out laterally, and having a series of teeth, and a rotating adjuster arranged to turn about an axis parallel or coincident with the axis of the bit, and having a spirally curved portion engaging the teeth of said arm, substantially as described.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

THOMAS E. POPE. Witnesses:

H. B. DENSON,

F. M. WRIGHT.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

